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Topic Review (Newest First)

06-12-2012 02:13 AM

mitiempo

Re: Possible alternative to Reflectix?

I don't see that it makes any difference if the inner layer is touching anything - besides that is impractical.

06-12-2012 01:59 AM

Jgbrown

Re: Possible alternative to Reflectix?

Yes So long as the inner layer is reflective, and not touching anything. Equally as effective as non-bubble wrap/foam/non-bubble wrap.
I would like to find a way to test these combinations, it could be invaluable. But surface temperature on the backside won't tell the whole story, so I"m not sure how to test.

06-12-2012 01:01 AM

mitiempo

Re: Possible alternative to Reflectix?

Sounds like my idea of Reflectix/foam/Reflectix in the V-berth is a good idea.

I wouldn't disturb a hull/deck joint that isn't leaking. They are probably just stained from years of condensation.

06-12-2012 12:52 AM

Jgbrown

Re: Possible alternative to Reflectix?

I was just thinking about all the bolts in it, should I pull them and re-bed, they seem to go right through and some have a bit of rusty looking discoloration underneath. Figured better safe than sorry is to pull them and clean and put back in. Radiant works both ways for sure, but it's heat out that I'm more worried about, so I'm not sure how it would benefit me on the hull side, other than if some radiant heat would pass right through the foam, and reflecting it back would help. After reading a bit more about the different types of heat transfer I think a reflective layer as the innermost layer makes the most sense, as it prevents radiant heat from hitting the foam as much as possible, rather than the inner layer of foam warming up, then reflecting the radiant heat back that passed through it. Perhaps I should put it outside too. I wonder though if it just touching foam(which would be warmed by the radiant heat, and therefore allow heat to conduct right through) is why it needs a complete air gap on one side.

06-11-2012 01:31 PM

mitiempo

Re: Possible alternative to Reflectix?

Radiant works both ways - in or out. Reflectix as the outside layer will keep the boat cooler in a warm climate.

The strips aren't hard to install. Epoxy either plywood solid wood strips to the hull on 16" centers after light sanding and acetone cleaning. They will have to be wedged in place overnight. You should be able to do this to any areas where it is needed in one day.

The Ethafoam I use is smooth on the surface and pretty easy to clean.

I wouldn't mess with the hull/deck joint. The only way to really re-bed it properly is to remove the deck from the hull. If it doesn't leak the bolts should be fine.

06-11-2012 01:20 PM

Jgbrown

Re: Possible alternative to Reflectix?

The 2 layers is to protect the middle reflective layer somewhat, the acoustic foam has a durable "skin" on it, also a reason I am looking to it instead of some other foams and should be ok so long as protected from major scratches etc, but easy to clean with a sponge. Then either building a strip ceiling(hard, I have to glass in the vertical parts as I haven't got any).
Also because in some areas I can get away with the thickness, others I cannot so it makes it easier to just have 1 type of foam(assuming I need only 1 roll).
I wonder if there would be a big benefit to having the reflective material as the inner layer, since it would reflect any radiant heat before it warmed the insulation, slowing the thermal transfer more than if it were in the middle. I am trying to figure out how to test that, perhaps some samples and a heater, or maybe I need to create a box. Not really sure how, but I think it could make a big difference.

If radiant heat hits the foam, and is conducted(but no longer radiant) through the foam, the middle layer is questionable at best and an inside layer would be much better. I know for camping pads, mylar top vs mylar middle does make a big difference.
I'd love to see how you do it someday soon, I'm de-molding and washing my reflectix for re-use. One area they used it in and shouldn't have was over the bolts that hold the deck to the hull. How hard is it to re-do these bolts(pull out, seal with butyl tape replace or put back). It'd give me peace of mind to know there's no crevice corrosion on them, and stop any water entry.

So where reflectix is a bonus, why not use just the attic reflective on top of the foam, cheaper, thinner. Does it's job without trying to do the foam's. Save the expensive reflectix for where I can't use the other stuff.
I am thinking 2 layers foam, 2 reflective, same as you basically, just in thinner layers and without the bubbles. total thickness 1/2-3/4"

I wonder if it would be more efficient to have a layer of reflective on the inside, since it would reflect the energy before it warms the insulation and turns to conducted energy instead.

The attic reflective is probably as effective as Reflectix as long as it is used with foam. As I posted a while ago Reflectix has increased in price since last year - I paid about 89 for the largest roll at Home Depot.

The foam I have and will use is Ethafoam in 1/2" thickness. If you are using 2 layers to get the thickness why not use a thicker foam - it is easier to apply.

I don't think you would gain anything by adding foil on the inside. I would make it the first layer.

A friend lives on a Spencer 35 that was insulated with 1/2" Ethafoam over 20 years ago. It is the warmest boat I have been on in cold weather. It has held up well. The only problem is that it can get dirty and in his case the cat has scratched it in a few places. I think the best solution (if you have a cat or not) is to line the insulation with something that can be wiped down easily.
My V-berth area has vertical beams glassed in 16" apart so the easy solution is to insulate between them to their 1" thickness and then line with something. I will probably use varnished wood strips here. In the lockers I plan to epoxy in strips the same thickness as the insulation and line with something like the plastic sheets that are about 1/16" to 1/8" thick and easy to keep clean.

Below the waterline I will not insulate I don't think. Under berths and seats one good solution is plastic carpet runner that has the protrusions on the back to grip a carpet. These will keep it off the hull and allow some air flow.

I want the foam for it's sound deadening/impact(my head against ceiling/beams).

You have to learn to duck where the headroom is restricted.

06-11-2012 03:03 AM

Jgbrown

Re: Possible alternative to Reflectix?

So where reflectix is a bonus, why not use just the attic reflective on top of the foam, cheaper, thinner. Does it's job without trying to do the foam's. Save the expensive reflectix for where I can't use the other stuff.
I am thinking 2 layers foam, 2 reflective, same as you basically, just in thinner layers and without the bubbles. total thickness 1/2-3/4"
I want the foam for it's sound deadening/impact(my head against ceiling/beams).

I wonder if it would be more efficient to have a layer of reflective on the inside, since it would reflect the energy before it warms the insulation and turns to conducted energy instead.

I just can't see how one works and the other doesn't, something fishy about that.

Which one isn't supposed to work?

As far as I know they all work to differing degrees. R value is one factor of course with foam winning over Reflectix. But the Reflectix is best at reducing the radiant. And the foam is best at the conductive.

If you are using only one make it closed cell foam. The Reflectix is an added bonus. This would be my choice for the hull. In the V-berth area I would insulate the most because that is where there is the most body heat near the hull sides when sleeping. My boat is getting a layer of Reflectix followed by 1/2" closed cell foam and then another layer of Reflectix, followed by wood trim in the V-berth area.

In the main cabin there are usually cabinets with dead space between the hull and any seating so a single layer of foam works well.

If you have to in some places use Reflectix by itself. This is not a bad choice for a location like the deck where the core is already acting as an insulator.

In all places whatever you use should be sealed well around the edges.

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